Increased hairballs without increased BG

Hello! First off this site and forum has been so instrumental in me successfully treating and testing my Sebastian since his diagnosis last year, so thank you so much! I tried searching posts for our current issue but couldn't find anything with our same situation. Please let me know if you know of this occurring with other diabetic kitties. Here is the background:
In Feb we started feeding Sebastian 3x/day since he wasn't gaining enough weight, was always hungry and his blood sugar numbers were fine with treatment. We are very regular with his feeding and insulin schedule. He has successfully gotten to a much better weight, I cannot feel his hip bones anymore and it didn't affect his BG numbers. Then in March we moved completely from Royal Canin Glycobalance wet to FF Classics pate and have tested to ensure his numbers were still good. We reduced him to 1.25 units and he has held steady since. We made this change due to the carb count in Royal Canin and the cost. If his issues are from the change though I will go back to Rx food. Lately he has pretty consistently been having hairballs around 2-4am almost nightly. I have a vet appt scheduled for tomorrow to run tests. He doesn't vomit any food, he has been eating/ drinking normally, he has been urinating normally, he has his normal energy and even gets hyper after meals and loves to play. So just wondering if this is something others have experienced? Thanks in advance!

 

Ok I have found a clue. We haven't been able to test 5 hours after his meal lately and he typically hits his nadir at 4-5 hours post meal. So if his hour 4 number was ok we called it good for the night. I am off work today so I was able to test him at 5 hours and he is hypo at 31. I will be giving him gravy lovers and monitoring. Could it be he is bouncing and since he doesn't get a midnight meal similar to midday meal that it is causing his hairballs?

 

Since days are getting longer cats shed more so more hairballs would be expected at this time of year than earlier.

 

Thank you for your response! I thought that the season change may be part of the reason but he has some pretty small hairballs, like an inch long at least every other day. Pretty atypical for his hairballs which has us worried. Usually they are bigger.